AUDIO TELEX ACM250 User manual

Australian Monitor
1 Clyde Street, Silverwater NSW 2128 Australia
[phone]
www.australianmonitor.com.au
SERVICE INFORMATION
AUDIO TELEX
ACM250
MIXER AMPLIFIER
CONTENTS:
OPERATION MANUAL
SCHEMATIC DIAGRAMS

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ACM250
Mixer Amplifier
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Audio Telex Communications Pty Ltd
ACN 001345482 lncorporated in NSW
NSW & ACT QLD & NT
149 Beaconsfield Street
Private Bag 149
Silverwater NSW 2128
Australia
Ph 02 9647 1411
Fax 02 9il8 3698
42 CommercialRoad
PO Box 871
Fortitude Valley QLD 4006
Ph 07 38521312
Fax [phone]
221277 Middleborough Road
Box HillVlC 3128
PO Box 151
Blackburn South VIC 3130
Ph 03 98907477
Fax [phone]
299 Fitzgerald Street
West Perth WA 6005
PO Box 404
North Perth WA 6906
Ph 08 92284222
Fax [phone]
Electronic Concepts Pty Ltd
76 George Street
Thebarton SA 5031
PO Box 7034 Hutt Street
Adelaide SA 5000
Ph 08 82349444
Fax [phone]
K W McOulloch Pty Ltd
54a Albert Road
MoonahTAS 7009
Ph 03 6228 6373
Fax [phone]
Unit B, 11 Piermark Drive
PO Box 512
Albany NZ 1331
Ph 09 4159426
Fax [phone]

ACM250 Mixer Amplifier
Product Description
The ACM250 mixer amplifier is designed for commercial installations. It operates on 240 VAC, 50Hz (or I l0 VAC, 60Hz with
factory modihcation) and may be desk or rack mounted via an optional rack mount kit. The ACM250 delivers 250 watts into a load of
4 ohms, 70 or 100 volt line. As standard, the ACM250 is supplied self standing with rubber feet. They may be stacked to a maximum
of four units high.
Front Panel Controls
IIIDIOIITTIT ACM250 o
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Dual Microphone/Line Gain Controls: The 6 dual mic/line input controls are labelled Ch 1 tbrough to Ch 6 and should
be adjusted to provide the required level mix for each individual channel. Start with the controls set to level 0 and turn the controls
clockwise until the desired mix level for each channel is reached.
Bass Contfol: Setting this control in the centre position will give an overall flat bass response. Adjusting the bass control in a
clockwise direction will provide up to 12 dB of bass boost @ 100 Hz. Adjusting the bass control in a counter-clockwise direction will
provide up to - 1 2 dB of bass cuI @ 100 Hz.
Mid ContlOll Setting this control in the centre position will give an overall flat middle response. Adjusting the mid control in a
clockwise direction will provide up to 12 dB of mid boost @ 600 Hz. Adjusting the mid control in a counter-clockwise direction will
provide up to -12 dB of mid cttt @ 600 Hz.
Tfeble COntfOl: Setting this control in the centre position will give an overall flat treble response. Adjusting the treble control
in a clockwise direction will provide up to 9 dB of treble boost @ 10kHz. Adjusting the treble control in a counter-clockwise
direction will provide up to -9 dB of treble cuI @ l0kJ1z.
MaStef OUtpUt COntrOl: This conhols the overall output level of the amplifier depending on the levels set for the individual
input channels as detailed above. Start with the control set to level 0 and tum clockwise until the desired output level of the amplifier
is reached.
POWer BUttOn: This switch controls the switching of AC power to the amplifier. A red neon within the switch will indicate
whether the amplifier is switched on or off.
PrOtect LED: A featwe of the ACM250 is high temperature protection. In most applications, the intemal cooling fan will most
probably never switch on. When used with demanding speaker loads or in diffrcult operating environments, the fatmay regularly
switch on to cool the amp down and then switch offagain. This switching on and switching offis quite normal. The "Protect" firnction
is there to protect the amplifier from a high temperatue problems which would only occur if the fan stopped working or became
clogged up. In this very rare occurance, the amplifier will shut down and the protect LED will illuminate. The amplifier will

automatically restart once it's intemal temperature has fallen within "safe" limits. If the protect LED illuminates, it is best to switch
the amplifier off, let it cool down and then try it again. If the protect LED illuminates again, please contact either Audio Telex or the
company who supplied or installed the equipment.
Rear Panel Connections
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AC FUSE
6A SB
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3 Pin IEC MainS Power lnlet Theoperatingvoltageis240VAC @50Hzor 110 vAC@60H2. TheACpowervolrage
is factory set and not externally user adjustable. The inlet is equipped with an inbuilt AC fuse holder fitted with a 6 amp fuse plus a
spare within the holder. Power consumption is 400 watts.
Please ensure that the mains power cord is disconnected before attempting to check or replace this fuse.
Direct Output Terminal Strip: The screw terminals on the left hand side of the strip allow access to the direct speaker
outputs of the amplifier. The screw terminals on the right hand side are for activation of the in-built 4 tone generator. Reading from
left to right the terminals are:
o Low Impedance Common (use with 4 ohms)
o 4 Ohms
' Spare
r Constant Voltage Common (use with 70v or 100v)
t 70 Volt Line
r 100 Volt Line
t Spare
o Tone Generator Common (use with one of the 4 tones listed below)
o Pre-Announce Chime
o Alert Tone
o Bell Chime
o Evacuation Tone
Note: The minimum impedance (or maximum load) at 100 Volt line should be no less than 40 Ohms.
Phantom Power Button: This button enables or disables the 18 volts DC phantom power which is available on all
microphone inputs (XLR's). The "in" position indicates that phantom power is on for all mics. The "out" position means that phantom
power is switched off for all mics. Phantom power is required for electret condenser microphones which require DC power to operate.
While some of these microphones can operate from an internal battery, having phantom power available on the amplifier eliminates
the need to regularly change batteries in the microphone. While phantom power is not required for the more common Dyramic
microphones, it will not damage them providing that they are balanced. Do not plug an unbalanced microphone in any amplifier or
mixer when phantom power is switched on.
Line Output The balanced XLR line level output provides a maximum of 700mV to allow for connection to up to 6 power
amplifiers. Simply run a balanced cable from the line out of the ACM250 to the line input of the power amplifier. Pin conaections are:
pin #l-earttr; pin #2-signal (high, +); pin #3-signal (low, -).

Tape OutpUt RCA style phono output corulectors provide a line level output with a maximum of 350mV into 1 0K Ohms which
is ideal for a connection to most standard tape recorders. This output is sourced before the master gain control and as such, the tape
output level is not influenced by the operation of the master gain control.
Active Balanced, XLR Sockets For The Microphone lnputs. The mic input sensitivity is lmV @ 200 ohms.
Pin connections are: pin #l-earth; pin #2-signal (high, +); pin #3-signal (low, -). Phantom power of +18 volts is available on all
microphone inputs. Reading from left to right across the rear panel, the connection are for microphone inputs 6, 5, 4, 3,2, & 1
respectively.
RCA Sockets For The Monaural Line Level Inputs. Line inputs 1,2,3, 4, & 5 have an input sensitivity of 75mV
@ 47K ohms. Input 6 has an input sensitivity of 300mV @ 47K ohms making it suitable for high level inputs such as a CD player.
Reading from left to right across the rear panel, the connections are for inputs 6, 5,4,3,2, & I respectively.
Other Features
TOng GgngfatOfS: Four separate tones are available from the in-built tone generator board. All four tones can be activated
individually via a contact closure connected to the screw terminals on the rear of the amplifier. To activate the bell chime for example,
just run a pair of wires from the Tone generator common and the Bell terminal to an extemal switch. Activating the switch, or closing
the pair of wires, will activate the bell. When any tone is activated, all inputs (except for inputs one and two) will automatically mute.
To adjust the level of the tone generator, disconnect the power lead, remove the amplifier lid and locate the pot labeled R6. (located
behind the Bass adjustment pot). This pot adjusts the level for all 4 tones.
Tones available on the ACM250 include:
o Evacuation Tone (to Australian Standard A52220.1.2)
o Alert Tone (to Australian Standard A52220.1.2)
o Bell Tone
r Pre Announce Chime
MUting: A VOX muting card is installed in the ACM250. This feature provides automatic muting of some channels when others are
active. It is normally used so that a paging microphone can have priority (by muting) over background music. VOX muting is available
from channels I and 2 meaning that any signal on channels I and2 (mic or line) will mute channels 3, 4, 5 & 6. The muted channels
will automatically ramp back up to normal volume when the signal on channels 1 and/or 2 is no longer active. The amplifier ships
with the VOX muting function enabled. To disable the VOX muting, disconnect the mains power lead and remove the lid of the
amplifier. Looking down from the front of the amplifier, a three position jumper (labeled JP2) is located just to the left and behind the
level pot for channel 1. To disable VOX muting, move the jumper to the middle and left pins. (Factory setting for VOX enabled is the
jumper on the middle and right pins).
Accessories:
Fuse Sizes: ACMRK: 19" rack mount kit
Mains, 240YAC:. 6 Amperes Slow Blow
DC: l0 Amperes Slow Blow

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VCC
VCC
VCC
VCC
C42
.1u
6L
5L
R54
220K
R53
47K
R52
4k7 R51 4k7
R50
10R
R49
4K7
R48
4K7
6XLR
5XLR
IC3A
LM1458
IC3B
LM1458
R47
680R
R46
680R
R45
47K
R44
22K
R43
22K
R37
22K
R36
22K
R35
220K
R34
680R
R33
680R
C41
4u7
C40
4u7
C39
4u7
C38
4u7
C37
150P
C36
150P
C35
150P
C31
150P
C30
4u7
C29
4u7
C28
4u7
C27
4u7
5R
6R
C32
4u7
D1
R32
10K
R31
10K
L
R
4R
3R
2R
1R
C24
4u7
C23
4u7
C22
4u7
C21
4u7
C20
150P
C19
150P
C18
150P
C17
150P
C16
4u7
C15
4u7
C14
4u7
C13
4u7
C12
4u7
C11
4u7
C10
4u7
C9
4u7
C8
150P
C7
150P
C6
150P
C5
150P
C4
4u7
C3
4u7
C2
4u7
C1
4u7
R22
680R
R21
680R
R20
22K
R19
22K
R18
22K
R12
22K
R4
220K
R17
47K
R16
680R
R15
680R
R14
680R
R13
680R
R11
47K
R10
22K
R9
22K
R6
22K
R5
22K
R3
47K
R2
680R
R1
680R
IC2B
LM1458
IC2A
LM1458
IC1B
LM1458
IC1A
LM1458
1XLR
2XLR
3XLR
4XLR
R7
4K7 R8
4K7
R23
4K7 R24 4K7
R25
4K7 R26 4K7
R27
10R
R29
4k7 R30 4k7
R38
47K
R39
47K
R40
47K
R41
220K
1L
2L
3L
4L
C33
.1u
C34
.1u
R42
10R
R28
100R
R55
4K7
R56
100R
R57
100R
V1
BD139
C43
4u7
C44
47u
C45
100u
D2
2OV
7XLR
R58
4K7
F1
10A SB
F2
10A SB
C25
.1u
VCC
ACM250 MIC INPUT
CD6238-1
CH 6 OUT
CH 5 OUT
AG
AG
AG
AG
AG
AG
12
3
4
76
5
8
+15V
PHANTOM
SW1
TAPE OUT
X1/1
(CD)
CH 4 OUT
CH 3 OUT
CH 2 OUT
CH 1 OUT
TAPE OUT
AG(1/2 VCC)
+VCC
+15V
8
8
5
67
4
3
21
5
67
4
3
21
RS
GND
GND
LINE OUT
X2/1
19VDC
+45VDC A
B
C

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File: C:\Protel Files\CDTRAX\CD6239-1.DDB Drawn By:
C22
47u
VCC
C33
100P
C32
100P
VCC
C30
4u7
C21
4u7
C11
4u7
C3
4u7
R53
1K
R52
1K
R50
1K
R49
33K
R48
10K
R47
10K
R46
10K
IC3B
LM1458
IC3A
LM1458
C2
.03u
C1 5N6
R19
50K R18
6K8
R4
6K8
R43
1M
R37
4K7
C19
470u D4
8V2
VCC
VCC
R22
5K6
V1
BC546
R21
150K
R20
10K
VCC
VCC
C17
820P
C16
4u7
C15
100P
C14 100P
C13
10u
C12
4u7
C8
4u7
C5
4u7
C4
4u7
D9
D5
D3
R17
22K
R16
4K7
R112M2
R3
10K
R2
5K6
R1
10K
IC4
LM3340
IC1B
1458
IC1A
1458
VCC
VCC
VDD
C36
10u
IC9
7805
R60
15K
C40
100u C44
820P
C45
.47u
C43
.47u
R63
1K
R62
10K
R64 100R
R65 220R
R66 1K8
D8
D7
D6
VDD
XT1
C42
22P
C41
22P
R61
10K
IC8
R40
50K
C39
100u
C38
4u7
R24
10K
C31
4u7
R44
1K
R42
3K3
R41
3K3
C29
2N7
C28 .03u
R39
50K
R38
50K
C27
82P
R36
10K
R35
6K8
R34
6K8
R33
100R
R32
1K
R31
100K
IC2B
LM1458
IC2A
LM1458
C25
4u7
R30
22K
R29
22K
R28
50K
R27
50K
R26
50K
R25
50K
R23
10K
R8
10K
R7
10K
C26
.47u
R6
10K
R9
100K
IC12
7809
C7
47u
R13
4K7
R14
3K9
R15
4K7
V2 BC546
C9
10u
C10
4u7
C18
330P
R45
10K
C23
4u7
C24
.1u
1
2
3
4
5
6
7
8
9
10
11
12
13
14 15
16
17
18
19
20
21
22
23
24
25
26
27
28
IC7
16C55
R55
10K
R56
560R
R57
470R
D1
V3
BC546
R58
10K
R5
50K
R10
50K
R59
10K
R67
100R
R68
1K
R69
1K2
C6
47u
R71
100R
R54
10R
C37
4u7
R51
10R
C20
4u7
R70
10R
R12
10R
C35
47u
C34
47P
R72
1K C46 100u
GND
OUT
OUT
TAPE
ACM250 MIXER
CD6239-1
5VDC
9VDC
13V
B
B
1
A
A
JP2
AG
AG
PRE AN
ALERT
BELL
EVAC
LM3340X4/1
X1/1
RS
5
67
8
4
3
21
TAPE OUT
AG(1/2VCC)
AG
AG
CH1
CH3
CH2
CH4
AG(1/2VCC)
1
X3/1 +19VDC
X2/2
X2/7
X2/8
FAN
FAN PTC
HT PTC
HI TEMP
X2/1
X2/3
X2/4
X2/5
X2/6
SLOW START
CH5
CH6
4X 10K
AG
AG
+9V
+19V
R70
A

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R96
100K
R97
100K
R98
100k
R95
10k
R94
47k
X5
VDD
X7
R78
330R
1
2
3
4 5
6
7
8
IC10
12C509
VDD
R77
100K
C26
.47
1
2 5
8
3 6
4 7
IC9
X9313
XT1
C25
4u7
C24
.1u
C23
47n
C22
22P
C21
22P
R76
1K R75 1K
R74
2K
R73
2K
R72
2K R71 2K R70 2K R69 2K
R68
2K
R67
1K
R66
1K R65 1K R64 1K
R63
1K R62 1K
A2
1
A3
2
A4
3
MC-
4
GND
5
B0
6
B1
7
B2
8
B3
9B4 10
B5 11
B6 12
B7 13
+5 14
OSC 15
OSC 16
A0 17
A1 18
IC8
16F84
IC11A
LM358 C20
.47u
R61
10K
D6
VCC
VCC
R56
10R
R52
220R
V1
BC639
RY1
D8
6V8
C12
22u
R48
22K
D7
R47
10K
C8
.1u
D2
D5
D4
D3
INSERT
VCC R45
15K
R58
1K
VCC
IC7
2180C C6 4u7
C5
4u7
R43
1K
R60
1K
R59
1K
R57
820R
R55
10K
R54
2K2
IC2B
LM1458
IC5B
LM1458
IC3A
LM1458
IC6A
LM1458
R53
22K
VCC
R51
4k7
R50
15k
IC11B
LM358
R19
2k2
R17
100k
R13
2k2
R42
10K
C2
.03u
C1 5N6
R16
50K
R15
6K8
R4
6K8
R34
4K7
VCC
R18
120k
VCC
C11
47P
C10 47P
C9
47u
C7
4u7
C4
4u7
R14
22K
R111M
R3
10K
R2
100k
R1
10K
IC4
2180C
IC1B
1458
IC1A
1458
VCC
R37
50K
C18
4u7
R21
10K
C17
4u7
R40
1K
R39
3K3
R38
3K3
C16
2N7
C15 .03u
R36
50K
R35
50K
C14
47P
R33
10K
R32
6K8
R31
6K8
R30
100R
R29
1K
R28
100K
IC5A
LM1458
IC2A
LM1458
C13
4u7
R27
22K
R26
22K
R25
50K
R24
50K
R23
50K
R22
50K
R20
10K
R8
10K
R7
10K
C19
.47u
R41
10K
R5
50K
R10
50K
R46
10K
R49
100k
R44
100K
C3
4u7
D9
X1
X4
X3
IC6B
LM1458
R6
1K
R9
15K
R12
4K7
D1
VCC
VCC
IC3B
LM1458
VCC
VCC
X8
C46
4u7
C4747P
AG
2
1
2
1
SLOW START
7
6
5
4
3
2
1
FAN ON/OFF
FAN TEMP
HI TEMP
2
7
8
PRE AN
ALERT
BELL
EVAC
HI TEMP
2
JP3
76
12VDC
4
1
2
3
8
73
5
6
INPUT IC3A
8
5
3
AMIS250 MIXER
CD6239-1
JP2
AG
AG
RS
5
67
8
4
3
21
TAPE OUT
AG(1/2VCC)
AG
AG
CH1
CH3
CH2
CH4
1
CH5
CH6
EXT 500K POT
VOX RELAY
TAPE OUT
J
1
10
1
1
HI TEMP
AG
AG

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R42
1K
R37
1K
R36
100K
C7
4u7
D1
R35
100R
R32
1K5
R28
.1R
R27
.1R
C10
.1u
C9
.1u
D7
R1
68K
R2
68K
R3
10K
R4
10K
R5
680R
R6
680R
R7
100R
R8
100R
R9
100R
R10
100R
R13
1K
R14
1K
R15
150R
R16
150R
R17
1K
R18
1K
R19
470R
R20
470R
R21
10R
R22
10R
R23
470R
T3A
T3B
V1
V2
V3
V4
V10
V15
V11
V16
V5
V6
P1
500R
D4
R39
150R
C5
820P
R50
.22 R51 .22
C1
2u2
C2
2u2
R55
.22 R56 .22
R38
150R
D5
P2
500R
C6
820P
IC2
78L05
T2
V7
BC640
D6
T1
S1
C1. C2.
D8
D9
F3
4A SB
F2
10A SB
N1
R31
1K
IC1A
LM833
IC1B
LM833 R11 1K
R12
1K
R24
10K
R25
10K
R26
10K
R40
10K
R41
47K
R43
10K
C3
.47
C4
100P
C11
100P
V8
BD139
R45
4K7
D15
12V
V9
BC546
C13
2u2
C14
47u
R46
4K7
R47
2K2
D16
4V7
R48
70DEG
R49
100DEG
BR1
F1
10A SB
IC3
7818 C8
4u7
C15
100u
R44
470R
D2
C12
.47u
1/2 VCC
CD6240-1
ACM250 POWER AMP
GND
INPUT
X3/1
X1/1
4 OHM
X2/9
X2/7
XT/5
X2/4
X2/2
X2/1
X2/3
X2/8
X2/6
240VAC
COM
COM
70VAC
100VAC
11
RS
FAN
TEMP FAN
TEMP CUTOUT
+45VDC
+45VDC
NC
FAN
V10-V19=TIP35C
R50-59=.22R
PLEASE NOTE:
BC639
BC639

1 2 3 4 5 6 78
A
B
C
D
8
7654321
D
C
B
A
Title
Number RevisionSize
A3
Date: 14-Apr-2004 Sheet of
File: C:\PDF CCT\CD6240-12.DDB Drawn By:
C12
.47u
D2
R44
470R
C15
100u C8 4u7
IC3
7818
F1
10A SB
BR1
R49
100DEG
R48
70DEG
D16
4V7
R47
2K2 R46
4K7
C14
47u
C13
2u2
V9
BC546
D15
12V
R45
4K7
V8
BD139
C11
100P
C4
100P
C3
.47
R43
10K
R41
47K
R40
10K
R26
10K
R25
10K
R24
10K
R12
1K
R11
1K
IC1B
LM833
IC1A
LM833
R31
1K
N1 F2
10A SB
F3
6.3A-SB
D9
D8
C2.C1.
S1
T1
D6
V7
BC640
T2
IC2
78L05
C6
820P
P2
500R
D5
R38
150R
R56
.22
R55
.22
C2
2u2
C1
2u2 R51
.22
R50
.22
C5
820P
R39
150R
D4
P1
500R
V6
V5
V16
V11
V15
V10
V4
V3
V2
V1
T3B
T3A
R23
470R
R22
10R
R21
10R
R20
470R
R19
470R
R18
1K
R17
1K
R16
150R
R15
150R
R14
1K
R13
1K
R10
100R
R9
100R
R8
100R
R7
100R
R6
680R
R5
680R
R4
10K
R3
10K
R2
68K
R1
68K
D7
C9
.1u
C10
.1u
R27
.1R
R28
.1R
R32
1K2
R35
100R
D1
C7
4u7
R36
100K
R37
1K
R42
1K
A
BC639
BC639
PLEASE NOTE:
R50-59=.22R
V10-V19=TIP35C
FAN
NC
+45VDC
+45VDC
TEMP CUTOUT
TEMP FAN
FAN
SBG
11
100VAC
70VAC
COM
COM
240VAC
X2/6
X2/8
X2/3
X2/1
X2/2
X2/4
XT/5
X2/7
X2/9
4 OHM
X1/1
X3/1
INPUT
GND
ACM250 POWER AMP
CD6240-1
1/2 VCC

123456
A
B
C
D
654321
D
C
B
A
Q1
TIP42C
R1
10K
R2
470K Z1
24V
C1
470UF 50V
RL1
SPST
OUTPUT TRANSFORMER
TRANS5
V+ 35V
GND
TO OUTPUTS
TO OUTPUTS
TO SPEAKERS
ACM250 DETHUMP
REV 1 Drawn by A.Dias
D1
1N40001